The present invention relates to an optical image reading apparatus and, more particularly, to one suitable for reading color documents.
With an image reading system which uses an imaging optical system with a high resolution and a spatially dividing type photoelectric conversion device, a problem arises in that moire phenomena occur when reading dot pictures. On the other hand, in a color document reading system which uses a dot sequential type color filter assembly and a spatially dividing type photoelectric conversion device (CCD), one picture cell is formed of a plurality of photoelectric conversion elements. In the case of a proximity type sensor using spatially dividing type photoelectric conversion elements, which arranged to read a document by a magnification of 1:1, different regions within one picture cell are read by a plurality of photoelectric conversion elements. For this reason, false color noise will be generated when minute irregularities, density variation (color variation, image variation, etc.) and/or local brightness variation of illumination light, occur in a document surface which falls within the area of one picture cell. For example, where a dot picture is reproduced, false color noise in which the color and brightness periodically vary due to a moire phenomena is generated.